1. Field of the Invention
The present invention relates to producing aligned carbon-nanotube aggregates and, in particular, to methods and apparatus for producing carbon-nanotube aggregates.
2. Description of the Related Art
Carbon nanotubes (hereinafter referred to also as “CNT” or “CNTs”) are carbon structures that exhibit a variety of properties. Many of the properties suggest opportunities for improvements in a variety of technology areas. These technology areas include electronic device materials, optical materials as well as conducting and other materials.
A known method for producing such CNTs is a chemical vapor deposition method (hereinafter referred to also as a “CVD method”). Prior art CVD methods involve preparing a catalyst with a reducing gas (to eliminate oxidation), then bringing a carbon-containing gas (hereinafter referred to as “raw material gas”) into contact with a catalyst, (i.e., fine metal particles in a hot atmosphere of approximately 500 degrees Celsius to 1,000 degrees Celsius). This results in CNTs with variations in aspects such as the type and arrangement. The CVD method has been used to produce both single-walled carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs), and is capable of producing a large number of CNTs aligned perpendicularly to a surface of the substrate.
One attempt to scale production of CNTs has been provided in U.S. Pat. No. 7,897,209, entitled “Apparatus and Method for Producing Aligned Carbon-Nanotube Aggregates.” The unit disclosed therein provides for mass production of CNT. However, as the formation unit and the growth unit are provided separately, a reducing environment is used, and for other reasons, the process therein is complicated and requires additional handling. In short, there is room for improvement.
Thus, what are needed are methods and apparatus for production of carbon nanotubes in a high throughput environment. Preferably, the methods and apparatus offer reduced cost of manufacture, as well as an improved rate of production.